2-oxo-3 spiropyran quinoxalines

ABSTRACT

Spiropyrans based on 1,2,3,4-tetrahydroquinoline compounds, a process for their manufacture and their use as dye-forming components in copying processes.

United States Patent 1 Oberlinner et al.

[ 2-OXO-3 SPIROPYRAN QUINOXALINES [75] Inventors: Andreas Oberlinler,Mannheim;

Hans Baumann, Ludwigshafen; Klaus Grychtol, Bad Durkheim all of Germany[73] Assignee: Badische Anilin- & Soda-Fabrik Aktiengesellschaft,Ludwigshafen (Rhine), Germany 221 Filed: June 21,1973

211 Appl.Nor:372,298

[30] Foreign Application Priority Data June 2|, [972 Germany 2230225July 22,1975

[56] References Cited UNITED STATES PATENTS 3.366.628 1/1968 Wendi eta]. 260/250 O OTHER PUBLICATIONS Hubib, Proc. Chem S00, (1961), pp.167-168 Primary Examiner-Donald G. Daus Asxixran! Examiner-David E.Wheeler Attorney, Agent. or FirmJ0hnston, Keil, Thompson & Shurtleff[57] ABSTRACT Spiropyrans based on l,2 3,4-tetrahydr0quinolinecompounds. a process for their manufacture and their use as dye-formingcomponents in copying processes 4 Claims. No Drawings 2-OXO-3 SPIROPYRANQUINOXALINES This invention relates to spiropyrans of formula I:

in which R is hydrogen, alkyl, cyanoalkyl. carboalkoxyalkyl ormethoxyalkyl each of from I to 6 carbon atoms or phenyl.

R is alkyl of from l to 4 carbon atoms.

A is a benzene nucleus optionally substituted by methyl, chlorine.bromine or alkoxy of from l to 4 carbon atoms, and

B is a benzene or naphthalene nucleus substituted by chlorine. bromine.nitro. alkyl, alkoxy or dialkylamino having from l to 5 carbon atoms ineach alkyl group.

The spiropyrans of formula I are compounds having little or no color.When dissolved in non-polar or weakly polar solvents such ashydrocarbons. chlorohydrocarbons and esters. they give intense red toblue colorations when acid substances are added. This reaction, which isalso caused by kaolin. zeolites, bentonite. silicic acid and phenoliccondensation products, makes the compounds suitable for use asdye-forming components for pressure-sensitive recording materials.particularly copying papers.

Preferred meanings of R are for example hydrogen.

methyl, ethyl. cyclohexyl. B-cyanoethyl. B-carbomethoxyethyl and'y-methoxypropyl.

Particularly preferred meanings of R are methyl and ethyl.

The number of substituents on the benzene nucleus A is preferably zeroor l. a particularly preferred substituent being methyl or chlorine inthe position 6 or 7.

Preferred examples of substituents on the aromatic nucleus B arechlorine. bromine. methyl. ethyl. t-butyl. methoxy. ethoxy,dimethylamino. diethylamino and carbomethoxy, the number of substituentsbeing preferably l or 2.

The spiropyrans of formula I may be conveniently prepared by condensingheterocyclic methylene bases or their salts with o-hydroxybenzaldehydesor o hydroxynaphthaldehydes via compounds of formula II as illustratedin the scheme below:

N O I N the ring closure to the pyran being catalyzed by bases. Examplesof suitable starting materials are as follows:

methylene bases l-methyl-2methylene-3-oxo-l ,2,3 .4-

tetrahydroquinoline.

l.4-dimethyl-2-methylene-3-oxo-l .2.3 .4-tetrahydroquinoxaline,

l -methyl-4-ethyl-2-methylene-3-oxo-1 .2.3.4-tetrahydroquinoxaline,

l-methyl-4-cyclohexyI-Z-methylene-3-oxol .2.3 .4-tet rahydroquinoxaline,

l-methyl-4-(B-cyanoethyll-2-methylene-3-oxol.2.3,4-tetrahydroquinoxaline.

l-ethyl-4-('y-methoxypropyl)-2-methylene-3-oxol.2.3.4-tetrahydroquinoxaline.

l.4-dimethyl-6-chloro-2-methylene-3-oxo-l .23 .4-tetrahydroquinoxaline.

l-ethyl-o-methyl- 2-methylene-3-oxo-l .2 .3.4.-tetrahydroquinoxaline.

l-ethyl-7-methyl-2-methylene-3-oxol .2.3,4-tetrahydroquinoxaline. and

l-methyl-4-phenyl-2-methylenc-3-oxol .2.3.4.-tetrahydroquinoxaline;

aldehydes Z-hydroxybenzaldehyde. S-chlorohydroxybenzaldehyde.5-bromohydroxybenzaldehyde. 3.S-dichlorohydroxybenzaldehyde.6-methoxy-2-hydroxybenzaldehyde. 5-t-butyl-Z-hydroxybenzaldehyde.4-dimethylamino-Z-hydroxybenzaldehyde.4-diethylamino-2-hydroxybenzaldehyde. 2-hydroxyl-naphthaldehyde. andZ-hydroxy-3-carbomethoxy l -naphthaldehyde.

The condensation of the methylene base with the aldehyde is convenientlycarried out in organic solvents such as alcohols, carboxylic acids.carboxylic anhydrides. carboxamides and hydrocarbons and optionally inthe presence of acidic or basic condensing agents such as zinc chloride.phosphoric acid. toluenesulfonic acid. boric acid. pyridine. piperidine.triethylamine and ammonium acetate. in amounts usually used forcondensation reactions of this kind and under the usual conditions. Thering closure to the pyrane may take place at the same time as orsubsequently to the condensation in the same or a separate stage by theaction of a base, for example alkali metal hydroxides. sodium carbonate.sodium acetate. ammonia. aliphatic amines or pyridine. in known manner.The crystallized spiropy- R1 OCH o E -H2O HO I 20 CH=CH rane compoundsprecipitated from the solution may then be used in known manner asdye-forming components in copying processes. For example, they may beworked into a paste which is then coated onto paper and overcoated witha protective layer. A particularly advantageous method is to use thedye-forming components in solution in for example chloroparaffin,chloroesters. diphenyl or toluene, and encapsulate the solution inmicrocapsules, with which the paper surface is then coated. When thislayer is pressed (for example by a writing operation) against a surfacewhich has been coated with an acid reacting substance, the dye is developed and fixed.

In the following Examples the parts and percentages are by weight.

EXAMPLE l 30 parts of l .2.4-trimethylquinoxaloniummethylsulfate and 14parts of salicylaldehyde are dissolved in 50 parts of ethanol and mixedwith l parts of piperidine. whereupon the mixture is heated under refluxfor 8 hours. When condensation is complete, the precipitate is filteredoff and washed with a little cold ethanol. There are obtained parts ofl,4-dimethyl-3- oxo-spirol l .2.3,4-tetrahydroquinoxaline 2,2'-(2H,l')benzopyran] in the form of colorless crystals having a meltingpoint of 174C.

A solution of this compound in chloroparaffin is enclosed inmicrocapsules which are coated onto the surface of paper. When this ispressed against an acid reacting layer by a writing operation, a redcoloration results.

EXAMPLE 2 60 parts of l ,2,4trimethylquinoxaloniummethysulfate and 38.6parts ofdiethylaminosalicylaldehyde are heated under reflux for minutesin MO parts of ethanol. The dye which precipitates as crystals oncooling is filtered off and stirred in 1,500 parts of benzene withaqueous ammonia until the color disappears completely. The benzene phaseis clarified with activated charcoal. dried over sodium sulfate andconcentrated to one fifth of its original volume. The reaction productis precipitated from the benzene solution by the addition of 500 partsof light naphtha to give 53 parts of l .4-dimethyl-3-oxo-7'-diethylamino spiro[ l,2,3.4.-tetrahydroquinoxaline-Z,2(2'H.l')benzopyrane], m.p. 152-l54C. Microcapsules containing the abovecompound dissolved in chlorinated diphenyl give a bluish violetcoloration when ruptured by a writing operation.

EXAMPLE 3 l5 parts of l ,2.4-trimethylquinoxaloniummethylsulfate and 7.6parts of o-vanillin-3-methoxy-(2- hydroxybenzaldehyde) are heated underreflux in 50 parts of ethanol for 1 hours. The dye is isolated andstirred with ammonia and benzene as described in Example 2 until thecolor disappears completely. Addition of light petroleum to theconcentrated benzene solution gives l,4-dimethyl-3-oxo-8-methoxyspiro[l.23,4,-tetrahydroquinoxaline-2,2'-(2'H,l benzopyran] in the form ofcolorless cyrstals having a melting point of l90-l92C.

Microcapsules containing a solution of the above compound give a redcoloration when pressed against an acid reacting layer by a writingoperation.

EXAMPLE 4 l 5 parts of l ,2,4-trimethylquinoxaloniummethylsulfate andl7.2 parts of B-oxynaphthaldehyde are heated under reflux for 18 hoursin ml of ethanol to which 20 parts of piperidine have been added. Theproduct which precipitates on cooling is filtered off and dissolved inbenzene for further purification, clarification being effected withanimal charcoal. The benzene phase is concentrated and the product isprecipitated therefrom in the form of colorless crystals by the additionof light petroleum. The thus obtained 1,4- dimethyl-3-oxo-spiroI1,2,3,4-tetrahydroquinoxaline- 2,2'-(2'H)naphtho[2, l-b]pyranl melts atfrom 122 to l24C.

Microcapsules containing this compound as dyeforming component give aviolet coloration when pressed against an acid reacting layer by awriting operation.

EXAMPLE 5 30 parts of 1,2,4-trimethylquinoxaloniummethylsulfate and 23parts of 2-hydroxy-3- EXAMPLE 6 l0 parts of l,2-dimethyl-4-(B-cyanoethylquinoxaloniummethylsulfate and 6 parts of diethylaminosalicylaldehydeare heated under reflux for l hour in 50 parts of ethanol. The dye isisolated and stirred with ammonia and benzene as described in Example 2until the color disappear completely. The benzene solution isconcentrated and precipitation of 1- methyl-3-oxo-4-( B-cyanoethyl)7'-diethylaminospiro[ l ,2,3,4-tetrahydroquinoxaline-2,2 (2'H,l')benzopyran] in the form of colorless crystals is effected by theaddition of light petroleum, the precipitated produce having an m.p. ofl44l46C. The yield is 6.5 parts.

Microcapsules containing the above compound give a blue coloration whenruptured against an acid reacting layer by a writing operation.

EXAMPLE 7 34 parts of l ,2-dimethyl-4-( B-cyanoethylquinoxalonium-methylsulfate and l2 parts of salicylaldehyde are heatedunder reflux in parts of alcohol for 4 hours. The dye is isolated and,as described in Example 2, decolorized with ammonia.

There are obtained 20 parts of l-methyl-3-oxo-4-(B- cyanoethyl )-spiro[1,2,3,4-tetrahydroquinoxaline-2,2 (2H,l')benzopyran]. mp. 169C.

When contacted with an acid reacting substance, this compound gives ared coloration.

EXAMPLE 8 EXAMPLE 9 24 parts of l.2.4-trimethylquinoxaloniummethylsulfate and 17 parts of dimethylaminosalicylaldehyde are heatedunder reflux in 170 parts of alcohol for l hour. Decolorizing of theisolated dye is effected as described in Example 2. The yield ofcolorless l,4-dimethyl- 3-oxo7 dimethylamino-sprio[ l,2.3.4.-tetrahydroquinoxaline- 2,2'-(2'H,l)benzopyran], mp. l72-l74C. isparts.

Microcapsules containing this dye-forming component give a bluish violetcoloration when pressed against an acid reacting layer by a writingoperation.

EXAMPLE l0 l0 parts of l,2-dimethyl-4-ethylquinoxaloniummethylsulfateand 6 parts of dimethylaminosalicyclaldehyde are heated under reflux in40 parts of alcohol for 2 hours. On completion of the condensation, thedye is isolated and decolorized as in Example 2. There are obtainedcolorless crystals of l-methyl-3-oxo-4- ethyl-7'-dimethylamino-spiro[ l2,3,4- tetrahydroquinoxaline-Z ,2'-( 2'H,l ')-benzopyran m.p. l20l22C.

A bluish violet coloration is obtained when this compound is contactedby an acid reacting substance.

We claim: 1. Spiropyrans of the formula:

t it //O in which R is hydrogen. alkyl, cyanoalkyl. carboalkoxyalkyl ormethoxyalkyl each of from l to 6 carbon atoms or phenyl,

R is alkyl of from I to 4 carbon atoms,

A is a benzene nucleus optionally mono substituted by methyl. chlorine,bromine or alkoxy or from 1 to 4 carbon atoms, and

B is a benzene or naphthalene nucleus mono substituted by chlorine.bromine. nitro. alkyl. alkoxy or dialkylamino having from 1 to 5 carbonatoms in each alkyl group.

2. Spiropyrans as claimed in claim 1, wherein R and R" each denotesmethyl.

3. Spiropyrans as claimed in claim 1, wherein the aromatic nucleus B isa benzene nucleus substituted by diethylamino.

4. The spiropyran of the formula:

1. SPIROPYRANS OF THE FORMULA:
 2. Spiropyrans as claimed in claim 1,wherein R1 and R2 each denotes methyl.
 3. Spiropyrans as claimed inclaim 1, wherein the aromatic nucleus B is a benzene nucleus substitutedby diethylamino.
 4. The spiropyran of the formula: